1. Field of the Invention
The present invention relates to a method of manufacturing a liquid crystal display device, and more particularly, to a method of manufacturing a liquid crystal display device used as a flexible display in which a glass substrate is thinned and a display surface can be bent.
2. Description of the Related Art
A liquid crystal display panel contained in a liquid crystal display device is an image display device which fundamentally includes a liquid crystal layer injected between a first substrate and a second substrate, each being suitably a glass substrate, and which is based on the fact that the alignment direction of a liquid crystal is changed according to an electric field applied to the liquid crystal from a pixel selection electrode of one of the first substrate and the second substrate. At present, the development of a liquid crystal display device used as a flexible display in which the glass substrate of the liquid crystal display panel is thinned and a display surface can be bent has been advanced.
An example of a method of thinning the glass substrate includes a method of chemically polishing the glass substrate by an etching solution such as hydrofluoric acid. A conventional technology of the method of chemically polishing the glass substrate is disclosed in JP 2003-40649 A.
When the glass substrate is thinned and then a liquid crystal injection hole provided in a side surface of the glass substrate is sealed with a sealing material made of a resin, it is likely to cause a defect in which the sealing material leaks out of the upper and lower surfaces of the glass substrate because the glass substrate is thin. Therefore, the method of chemically polishing the glass substrate after the liquid crystal injecting process and the liquid crystal sealing process is efficient in terms of mass production.
However, the sealing material made of the resin is not dissolved by hydrofluoric acid. Therefore, during an etching process, the convection of the etching solution is inhibited, and hence an etching rate of the glass substrate becomes lower at a portion close to the sealing material, with the result that a thick portion of the glass substrate is locally produced at the portion close to the sealing material.
A local thickness difference of the glass substrate causes the breaking of glass or the remaining of bubbles during subsequent polarizing plate bonding, thereby degrading image quality.